―Ansem, Seeker of Darkness
Ansem, Seeker of Darkness is the main antagonist of Kingdom Hearts and the "Reverse/Rebirth" mode in Kingdom Hearts Re:Chain of Memories. He is the Heartless of Xehanort, and retains the dark "guardian" which belonged to his original self.
Prior to Kingdom Hearts Edit
In the pursuit of knowledge, Xehanort, at the time calling himself "Ansem", willingly gave his heart to the darkness, creating both his Heartless and his Nobody, Xemnas. His Heartless was able to retain its selfhood for uncertain reasons, though it was believed by the true Ansem that this was due to Xehanort's willing abandonment of his heart, which is reinforced due to the fact that Sora, the only other person ever to keep his mind as a Heartless, also willingly surrendered his heart.
He and legions of Heartless at his command continued his original self's pursuit of knowledge, believing it would be found in darkness, and stole countless hearts from both humans and worlds in search of this knowledge. But his ultimate goal was Kingdom Hearts, a supposed repository of tremendous power and knowledge. However, to access the heart of all worlds, he would need to open the Final Keyhole. For this, the Princesses of Heart were needed to complete the Keyhole. He also realized that the wielder of the legendary Keyblade needed to be found, for the Keyblade's ability to seal away the hearts of worlds from the preying Heartless could prove dangerous. So, believing that the Princesses and the Keyblade wielder are connected, he sent Kairi, a supposed resident of The Radiant Garden, as well as a Princess of Heart, to another world where a future Keyblade wielder lived and Xehanort's original home. As he waited for his theory to be proven, Ansem continued on his path towards stealing many hearts.